Landmark reforms of the UK pension system risk being undermined because a large number of Britons are simply unaware of them, a study claims.

AXA Wealth found that almost a third of UK adults did not know about the changes in the Budget that will give 13million defined contribution pension savers unrestricted access to their retirement pots, or how they'll be affected by them.

It is possible that this gap in knowledge is down to the fact that the changes won't affect them at all, either because they're already retired or because they are on a defined benefits pension, but Axa said there is evidence of a wider lack of understanding about retirement that is 'alarming'.

Lack of awareness: A third of adults are not aware of the changes announced in the Budget.

Of the potential retirement products available to people once pensions freedom kicks in, some 36 per cent said they hadn't heard of a single one, while AXA said adults who are actively engaging in planning their retirement are in minority.

Nick Elphick, of AXA Wealth, said: 'While the pension changes in the Budget constituted the biggest reform of pensions in over 100 years, it is alarming to discover the low levels of understanding and knowledge amongst UK adults.

'With the end of compulsory annuitisation, the flood gates have been opened to a whole new raft of at-retirement possibilities. It is crucial that industry help make investing as easy as possible.

'If pensions literacy is not improved, and the free financial advice pledged by the Chancellor is diluted or cannot be delivered on time, many people will not have sufficient means to support themselves during retirement.'

The Government has pledged to give people with defined contribution pensions access to guidance when they reach retirement to help them make the right decisions of what to do with their savings.

These savers will be given total control over their retirement pots, meaning they will no longer be obliged to buy an annuity with their savings, and instead can withdraw money as and when they like, only paying marginal tax on their withdrawals.

These people will still be able to buy annuities, but new products that recognise the flexibilities created in the Budget, like unit-linked guarantees, are now being marketed to future retirees in a bid to attract their business.

But knowledge of these products remains limited, putting the onus on whomever provides the guidance promised by the Government.

Annuities are still the most recognisable retirement products, with 58 per cent of people surveyed saying they are aware of them, but other options such as phased drawdown, retirement strategy funds and variable annuities were less well known.

Mr Elphick said: 'Two thirds of respondents said that their priority is maintaining their current standard of living into retirement, it is critically important that they take advice and fully consider their options - especially given that life expectancy is increasing exponentially.

'People need to be fully informed about the changes taking place if they are to take full advantage of the new investment options open to them that will help them boost their retirement income.'